Imaging scanners, or “imagers,” are increasingly replacing the laser scanner for many uses. This is because the imagers offer more features than laser scanners such as the ability to read two-dimensional barcodes and capturing images such as checks and identification documents. However, when processing one-dimensional barcodes, a laser scanner can often outperform an imager, especially a high-resolution imager. This is because of the additional time required for the imager to capture and process an entire image. For example, it is necessary for an imager to search the image to determine if a barcode is present anywhere in the image and if so, identify the type of barcode. This search for the presence of a barcode in the image stored in pixel data is generally done by analyzing sub-regions of the image and calculating statistics such as a level of contrast between pixels in the sub-region and directional vectors associated with detected edge lines. Based on the statistics one or more sub-regions are identified as potentially containing a barcode and each of these sub-regions is passed on for decoding. One example of a barcode detecting system can be found in U.S. Pat. No. 6,405,925 to He et al, assigned to the assignee of the present invention, and incorporated herein by reference in its entirety.
To improve the operation speed of imagers some decoding systems operate on data from a segment of the image frame. For example, U.S. patent application Ser. Nos. 11/341,950 and 11/395,569, assigned to Symbol Technologies, Inc. and incorporated herein by reference describe imagers that search for a simple one dimensional barcode in a pre-selected cropped portion of the image frame and resort to full frame processing in the event that no such barcode is found in the cropped frame after one or more decode attempts.